SYMPATHETIC NERVE. 



433 



organic nerve fibres. According to Purkinje *, 

 the ganglionic nerve-fibres are much finer 

 than those belonging to the cerebro-spinal 

 system or animal fibres. He describes the 

 latter as containing two substances, an outer, 

 which runs in the form of a tube through the 

 elementary fibre immediately within its sheath, 

 and an inner, which occupies the hollow in- 

 terior of the former. The tubular sheaths 

 of the elementary fibres of the ganglionic 

 system contain, on the other hand, no double 

 substance ; their contents are homogeneous, 

 and appear to correspond to the axis cy- 

 linder or central portion of the animal nerve- 

 fibres ; their sheaths are much stronger than 

 those of the nerve-fibres of the cerebro- 

 spinal nerves, and resist mechanical influ- 

 ences in a high degree. In the fetus the 

 animal nerve-fibres cannot, according to 

 Purkinje, be distinguished at a certain stage 

 of their formation from those which are cha- 

 racteristic of the sympathetic in the full-grown 

 animal ; and hence he regarded the latter as a 

 less highly developed stage of the former. 

 Pappenheim also appears to have recognised 

 the fibres described by Purkinje, as consti- 

 tuting the peculiar fibres of the sympathetic 

 system. 



According to Remakf, the fibres which 

 have been described above as the gelatinous 

 fibres or fibres of Remak, constitute the pe- 

 culiar organic or sympathetic nerve-fibre, all 

 the tubular nerve-fibres being considered by 

 him as belonging to the cerebro-spinal system. 

 The fibres in question do not take their origin, 

 according to him, from the cerebro-spinal 

 centres, but arise from the ganglionic corpuscles 

 contained in the different ganglia, and then 

 run along with the tubular fibres sent to the 

 sympathetic by the cerebral and spinal nerves. 

 It has been disputed, however, whether the 

 fibres described by Remak are entitled to the 

 character of nerve-fibres, and are not rather 

 to be regarded in the light of accessory struc- 

 tures which serve as a sheath to the true or 

 tubular nerve-fibres. Valentin , who adopts 

 the latter view, states that the fibres in ques- 

 tion do not arise from the ganglionic cor- 

 puscles themselves, as was believed by Remak, 

 but are continuous with the nucleated sub- 

 stance which forms the sheath or capsule of 

 these bodies, and are thence prolonged upon 

 the nerve-tubes, and are to be viewed as 

 merely discharging the part of a protecting 

 covering or envelope to the latter. They do 

 not, according to Valentin, present the most 

 distant resemblance to nerve-tubes, which 

 could scarcely be the case were they in reality 

 a mere variety of the same structures : in 

 their microscopic character, on the other 

 hand, they agree in every respect with certain 



* Midler's Archiv. 1839, p. 203. Valentin's Re- 

 pertorium, band v. p. 78. See also Bidder and 

 Volkman, op. cit. 



f Loc. cit. 



f Ueber die Scheiden der Ganglienkugeln und 

 deren Fortsetzungen, in Mailer's Archiv. 1839. 

 Also Valentin's Eepertnrium, baud iii. p. 70. et 

 serj., and band v. p. 79., &e. 



forms of white fibrous tissue, especially at 

 certain stages of its formation ; and they are 



Fig. 283. 



From the semilunar-ganglion of man. 



A. Ganglionic corpuscles included within their 

 nucleated capsules. 



B. Ditto liberated. 



entirely wanting, or occur only in small num- 

 bers, in the main cord of the sympathetic, where 

 the fibrous tissue is, as well as in many of the 

 peripherical branches of the same, deficient. 

 In the horse the fibres of Remak, which are 

 present in the nerve-branches passing along the 

 mesentery, were seen by Valentin to cease one 

 or two feet from the point at which the nerves 

 enter the intestine. Bidder* and Volkmann 

 also appear to regard them merely as a variety 

 of areolar tissue, observing that their anatomical 

 characters are so different from the known 

 elements of the nervous system as to exclude 

 them from the character of true nerve-fibres. 

 In the mammalia, according to these authors, 

 the areolar tissue which is interposed between 

 the different organs is very abundant, and in this 

 class of animals the fibres of Remak also abound. 

 In birds, where the quantity of such areolar 

 tissue is smaller, these fibres are not so nu- 

 merous ; and in the cold-blooded animals, 

 where there is very little interposed areolar 

 tissue, the fibres of Remak either fail al- 

 together, or they exist only in very small 

 numbers. From this it would appear that 

 they regard the fibres of Remak as holding 

 the same relation to the tubular nerve-fibres 

 that the areolar tissue holds to the different 

 organs between which it is interposed. They 

 also agree with Valentin in regard to the 

 very mWked resemblance between these fibres 

 and white fibrous tissue at certain stages of 

 its formation, and accordingly adopt the 

 view that they are rather to be regarded as 

 white fibrous tissue which has not reached its 

 full development than true nerve-fibres. They 

 find, moreover, as will be afterwards noticed, 



Op. cit, 12. 



F r 



